1. Field of the Invention
The present invention generally pertains to handheld medical devices, and more specifically to electrically driven lancets; epidural catheter inserters; biopsy medical instruments, such as bone biopsy medical devices; vascular entry penetrating members, spinal access needles and other catheterization needles. The invention is applicable to the delivery and removal of blood, tissues, medicine, bone marrow, nutrients or other materials within the body.
2. Description of Related Art
Epidural anesthesia is a form of regional anesthesia involving injection of drugs directly into the epidural space. To begin the procedure, a needle is inserted from the outer layer of skin, through several layers of tissue and finally placed within the epidural space, through which a catheter is optionally passed. Local anesthetics are injected into the epidural space causing temporary loss of sensation and pain by blocking the transmission of pain signals through nerves in or near the spinal cord. The procedure can be unpleasant to the patient because of the high force levels required for the relatively dull epidural needle to penetrate the supraspinous ligament, interspinous ligament and ligamentum flavum. One complication is that a clinician will accidently overshoot and puncture the dura because of this high force of penetration and an almost-instantaneous change in resistance upon passing the needle into the epidural space (i.e., high forward momentum followed by instantaneous minimization of force). Upon puncturing the dura, the cerebrospinal fluid can leak into the epidural space causing the patient to experience severe post dural puncture headache, lasting from days to possibly years. Significant leakage can cause enough intracranial hypotension as to tear veins, cause subdural hematoma, and traction injuries to the cranial nerves resulting in tinnitus, hearing loss, dizziness, facial droop, or double vision.
A bone marrow biopsy is used for diagnosing tumors and a variety of bone diseases. The most commonly used site for the bone biopsy is the anterior iliac crest. A major disadvantage is the force required to penetrate the bone tissue, and the twisting motion often used to force the needle inward, which results in patient discomfort as well as possible healing complications from damaged tissues. The penetration force can also be tiring for clinicians and lead to multiple sampling attempts. Complications are rare but can include bleeding, pain, and infection. Pain is minimized with proper local anesthesia, though the patient still experiences a pressure sensation during insertion and retraction during some procedures. Another problem is crushing the sample or being unable to retrieve part of all of it, limiting the ability to diagnose. As shown in FIG. 1, a biopsy tool PA1 typically comprises a handle (not shown) and hollow cannula 1 with cannula distal end 1′ surrounding a stylet 2 attached to the handle. To penetrate through cortical bone, a clinician pushes the cannula and stylet through the bone to the marrow. The distal tip 3 of the inner stylet or trocar is sharpened and has an angled chisel-like face 4 which reduces the surface area to reduce the exertion force.
Currently, to minimize the possibility of a dura puncture, the epidural catheter insertion process is typically performed very slowly and with a 16-18 gauge, specially designed, relatively dull needle PA2, such as the one shown in FIG. 2 called a Tuohy needle 5. An epidural needle, such as the Tuohy needle 5 or Hustead needle, has a directional curved tip 6, which decreases the “sharpness” at the needle and, therefore, makes accidental dura puncture more difficult. The curved tip also facilitates directing an indwelling catheter into the epidural space and a tip opening 7 facilitates catheter or fluid introduction or removal. Unfortunately, this dull curved-tip design actually increases the force a clinician must use and makes it more difficult for a clinician to stop the forward momentum upon penetration of the dural space. Additionally, the Tuohy design increases the likelihood that a clinician relies on tactile feedback during penetration. In other words, during the insertion procedure a clinician will rely on feeling a “popping” sensation—indicative of passing the needle past the ligamentum flavum—to locate the tip of the needle within the epidural space and quickly stop the forward momentum being applied. Still, because penetration into other tissues, such as muscle, calcified ligament, or regular ligament may produce a similar popping, a clinician may not fully perceive the correct location of the needle tip where the tip of the needle is occluded until passing through these tissues.
Several alternate technologies have been developed that attempt to minimize the dura puncture risk, while also giving the clinician indication of successful epidural placement. For example, the detection method and apparatus disclosed in U.S. Patent Application Publication No. 2007/0142766 (Sundar, et al.), the contents of which are incorporated by reference, relies on a spring-loaded plunger pushing a fluid into the epidural space upon successful entry. Accordingly, the clinician is given a visual indicator (i.e., the movement of the plunger as the fluid experiences a loss of resistance at the needle opening), and would cease applying forward force. Similarly, U.S. Pat. No. 5,681,283 (Brownfield) also relies on a visual indicator to communicate successful entry of a needle into a cavity to the clinician. Unfortunately, while a visual indicator is a positive advancement, the actual cause of the accidental dural wall puncture—that is, the high force applied by the clinician against the needle to pass through the various tissue layers and then stop—is not taught or suggested.
Therefore, there exists a need for a tool that reduces the puncture force of a needle, such as a Tuohy needle, and enables a clinician to perform a more controlled entry into the epidural space, thereby reducing the possibility of an accidental dura puncture.
While accidental dura puncture is a concern, simply locating the epidural space may pose a challenge even to the most skilled physicians. Therefore, when a needle such as a Tuohy needle is passed through the ligamentum flavum and into the epidural space, it is helpful for a clinician to receive immediate feedback indicating successful penetration and the location of the tip of the needle. A basic conventional feedback device such as the one in FIG. 2a comprises a needle (not shown) attached to a syringe PA3 at a front portion 9, and wherein the syringe PA3 is formed of a tubular body 10 and houses a biasing element 11 comprising a stem acting as a biasing element. To provide feedback indicating successful epidural penetration the device relies on a biasing force acting against the biasing element 11 which then acts upon a fluid, such as saline or air within the syringe. Essentially, in this hydraulic feedback method, as the biasing force acts upon the fluid, the fluid translates this pressure to an opening of the needle tip. An opposing force, acting on the needle tip as it is held against a tissue such as the ligamentum flavum, acts to prevent the fluid from being released from the syringe. Typically, a clinician's thumbs act as the biasing force source which in turn acts upon the plunger stem. The clinician's thumbs serve to “feel” the hydraulic resistance exerted on the fluid by the opposing tissue force. Upon entering the epidural space, however, the opposing pressure of tissue acting against the tip is removed, and a pressure drop allows the biasing force to move solution out of the syringe through the needle tip. The clinician becomes aware of successful penetration of the epidural space due to his/her thumbs “feeling” the sudden pressure drop or loss of resistance at the plunger stem. Also, the clinician may receive visual indication of successful penetration by witnessing the plunger advancing through the syringe externally as the fluid is released into the epidural space in the patient. One problem with this conventional device and method is that it is difficult for a clinician to both apply a biasing force on the plunger while also applying an advancing force against the syringe body in order to advance the needle through the ligamentum flavum; Moreover, to prevent accidental dura puncture, clinicians tend to hold the conventional syringe in such a way as to hold the patient steady, while applying a forward momentum against the syringe, and while applying a biasing force against the plunger stem. This is both awkward and uncomfortable to the clinician and patient.
Some advancements have also attempted to provide an automatic biasing element to act against the plunger of an epidural syringe while also providing visual indication or feedback, rather than tactile response, of successful puncture of various internal target areas in the human body. For example, in U.S. Patent Publication No. 2007/0142766 (Sundar et al.), a spring is utilized to act with a biasing force against the syringe plunger. When the epidural needle attached to the syringe passes through into the dural space, the pressure drop allows the spring to bias the plunger. As the plunger moves, the stem provides at least some visual indication as it moves with the plunger. Similarly, U.S. Pat. No. 5,024,662 (Menes et al.), which is hereby incorporated by reference, provides visual indication by utilizing an elastomer band to provide the biasing force against the plunger stem. In U.S. Pat. No. 4,623,335 (Jackson) which is hereby incorporated by reference, an alternative device assists in visually indicating a pressure to identify the location of the needle tip. In addition, U.S. Pat. No. 7,297,131 (Call) which is hereby incorporated by reference, uses a pressure transducer to translate a pressure change into an electronic signal. The electronic signal is then converted to a visual display indicator, for example by activating a light emitting diode to emit.
Therefore, a need exists to overcome the challenges not addressed by conventionally available technologies that reduces the force necessary for penetration of a sharp medical element of a medical device through tissue and also has the ability to deliver (e.g., deliver saline solution, or drugs, etc.) or retrieve materials subcutaneously (e.g., bone biopsy, etc.).
A need also exists to provide visual, tactile, electrical or additional indication to a clinician that the penetrating member has successfully penetrated the specific body space such as the epidural space, especially when the force to enter such a space has been substantially reduced. And this same force reduction must be either controlled or shut off immediately upon entry into the epidural space to avoid (easier) penetration of the dura.
Specifically, a need exists in the medical device art for an improved medical device having a penetrating element that is vibrated at a frequency that thereby reduces the force required to penetrate tissue, reduces the amount of resulting tissue damage and scarring, improving body space or vessel access success rate, minimizes introduction wound site trauma and, most importantly, improves patient comfort while minimizing potential complications.
A need exists for a clinician to be able to use less force to penetrate hard tissue such as the cortical bone during bone biopsy, which would reduce clinician fatigue, patient discomfort, and tissue damage while improving the sampling success rate and quality. There is a need to sense proper location, stop forward motion and collect the sample. There is a further need to turn device on after collection and to reduce force and patient discomfort as the penetrating member is being retracted from the body.
There is also a need for spinal access procedures where a clinician would want a reduction of force as well as to know the location of the needle tip but applied to a relatively-sharp penetrating member, such as a pencil point tip, as the clinician does not want to core tissue.
There is also a need for performing nerve block procedures where a clinician would want a reduction of force as well as to know the location of the needle tip. And this same force reduction must be either controlled or shut off immediately upon entry into the desired location.
All references cited herein are incorporated herein by reference in their entireties.